将变量传递到d3.js函数（d）

Question

Fairly new to d3.js, so there may be something obvious I'm missing. I'm trying to pass a string variable into a function(d) to calculate the "x" position of text labels based on another function. I've got the following (relevant) code:

function display_labels(category){
  var categories = vis.selectAll("."+category+"s")
                   .data(cat_data);
  console.log(category); // returns 'year' - correct
  categories.enter().append("text")
                    .attr("class", category+"s")
                    .attr("x", function(d) { 
                      console.log(category); // returns undefined - incorrect
                      // more code after this

How can I pass the string into the function so that it will work?

Answer 1

Further below in the code I had an if statement which incorrectly called the same function again with an undefined category. I was using:

if (category2 !== 'undefined') { display_labels(category2); }

Instead of:

if (category2 !== undefined) { display_labels(category2); }